Control system and architecture for incorporating microelectromechanical (mem) switches in fluid-based cooling of 3d integrated circuits

ABSTRACT

A cooling system is provided for a 3D integrated circuit (IC) to deliver fluid in x, y, and z dimensions to interior regions of the IC as a means to regulate heat. An IC includes a microfluidic network of channels, at least one sensor and at least one microelectromechanical system (MEMS)-based device that is disposed within the network of channels and that is configured to regulate a flow of fluid within the network of channels. Each sensor monitors a state of the IC. Each MEMS-based device receives control signals based on a state of the IC and regulates a flow of fluid within the network of channels based on control signals that area received on a real-time basis based on changes detected in a state of the IC.

BACKGROUND

Two-dimensional (2D) ICs have long been known to offer limited amount ofbandwidth that can be delivered to a processor. For example, for dataintensive workloads such as key-value stores, and distributed graphanalytics, the workload's working set is often too big to fit in thecentral processing unit (CPU) caches. As a result, off-chip memorybandwidth largely dictates the speed of the computation. However, due totheir planar design, heat dissipation for 2D ICs is simplified.

Two-and-one-half (2.5D) and three-dimensional (3D) ICs are composed ofmultiple die-bonded layers. In this case, memory bandwidth, for example,can be sizably increased at significantly reduced energy cost. However,one of the principal challenges is that heat generated in the hotcomponents of one layer heats up the layers directly above and/or belowit. This transference of heat makes 3D design challenging because itlimits the types of circuits that can be stacked on top of one another.For instance, when considering a processor-in-memory architecture, wherethe 3D memory is directly stacked on top of a separate logic-layer die,the ideal operating temperatures for the memory technology limit whatkind of logic can be incorporated in the logic layer. For instance, thecomplexity of the logic in a 3D design can be severely curtailed by thechallenge that a hot arithmetic logic unit (ALU) in a logic layer of the3D IC has the potential to corrupt the bits in dynamic random-accessmemory (DRAM) layers that are stacked above it, which necessitatesincreasing the refresh rate of the DRAM.

Accordingly, in terms of heat dissipation for 2.5D and 3D ICs, thecommon practice is to mount an air-cooled heatsink on the IC, haveliquid cooled loops, or to immerse the IC in an electrically insulating,non-conductive liquid such as mineral oil. For example, recent trends indata centers make use of liquid cooling of servers as well asfull-server immersion in a non-conductive fluid such as mineral oil inorder to dissipate heat. Although liquid cooling allows for allcomponents within a server chassis to be cooled as the fluid passesover, it does not provide the pinpoint accuracy needed to choreographdispersion of heat at the scales that can be present in 3D die-stackedchips.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding can be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 is a block diagram of an example device in which one or moredisclosed embodiments can be implemented;

FIG. 2 illustrates an example MEMS-based switch according to one or moredisclosed embodiments;

FIG. 3 illustrates an example 3D IC with a microfluidic channel networkaccording to one or more disclosed embodiments;

FIG. 4 illustrates another example 3D IC with a microfluidic channelnetwork according to one or more disclosed embodiments;

FIG. 5 illustrates a block diagram of an example control systemimplemented by one or more disclosed embodiments;

FIG. 6 is a flow diagram of a cooling method implemented by one or moredisclosed embodiments; and

FIG. 7 illustrates another example 3D IC with a microfluidic channelnetwork according to one or more disclosed embodiments.

DETAILED DESCRIPTION

In the following description, details are set forth to provide a morethorough explanation of embodiments provided herein. However, it will beapparent to those skilled in the art that the embodiments can bepracticed without these specific details. In other instances, well-knownstructures and devices are shown in block diagram form rather than indetail in order to avoid obscuring the embodiments. In addition,features of the different embodiments described hereinafter can becombined with each other, unless specifically noted otherwise.

Equal or equivalent elements or elements with equal or equivalentfunctionality are denoted in the following description by equal orequivalent reference numerals even if occurring in different figures.

A temperature regulating system for three-dimensional (3D) integratedcircuits (ICs) is provided. In particular, the temperature regulatingsystem is provided for a complex networked system of microfluidicchannels that crisscross within a 3D IC in the x, y, and z dimensions todeliver fluid to interior regions of the IC as a means to dissipate heator otherwise regulate temperature.

An IC includes a plurality of channels configured to carry a fluidtherein through internal portions of the IC. The plurality of channelsinclude a first channel and a second channel. At least one sensorconfigured is provided to sense at least one state of the IC. Amicroelectromechanical system (MEMS)-based device is disposed at ajunction connecting at least the first channel and the second channel ofthe plurality of channels. The MEMS-based device is configured toreceive control signals from a controller based on the at least onestate of the IC and is configured to regulate a flow of the fluid fromthe first channel to the second channel based on the control signals.

Another IC includes a first sensor configured to measure a state of theIC at a first location of the IC. The IC further includes a microfluidicnetwork of channels configured to carry a fluid therein through internalportions of the IC The microfluidic network of channels include a firstchannel that is disposed in proximity to the first location such that atemperature at the first location is regulated by a flow of the fluid inthe first channel. A microelectromechanical system (MEMS)-based deviceis disposed within the microfluidic network of channels. The MEMS-baseddevice is configured to receive control signals from a controller basedon the state of the IC at the first location, and to regulate the flowof the fluid in the first channel based on the control signals.

A method of cooling an IC is provided in which the IC includes amicrofluidic network of channels, at least one sensor and at least onemicroelectromechanical system (MEMS)-based device disposed within themicrofluidic network of channels and configured to regulate a flow offluid within the microfluidic network of channels. The method includesmonitoring, by the at least one sensor, a state of the IC. The methodfurther includes receiving, by the at least one MEMS-based device,control signals from a controller based on the state of the IC. Themethod further includes regulating, by the at least one MEMS-baseddevice, the flow of fluid within the microfluidic network of channelsbased on the control signals received by the at least one MEMS-baseddevice on a real-time basis based on changes detected in the state ofthe IC.

FIG. 1 is a block diagram of an example device 100 in which one or moredisclosed embodiments can be implemented. The device 100 can beimplemented in a temperature regulating system or in a controllerconfigured to route fluid in a networked system of microfluidic channelsthat crisscross within a 3D IC in the x, y, and z dimensions to deliverfluid to interior regions of the IC as a means to dissipate heat orotherwise regulate temperature. The device 100 can include, for example,a computer, a gaming device, a handheld device, a set-top box, atelevision, a mobile phone, or a tablet computer. The device 100includes a processor 102, a memory 104, a storage 106, one or more inputdevices 108, and one or more output devices 110. The device 100 can alsooptionally include an input driver 112 and an output driver 114. It isunderstood that the device 100 can include additional components notshown in FIG. 1.

The processor 102 can include a central processing unit (CPU), agraphics processing unit (GPU), a CPU and GPU located on the same die,or one or more processor cores, wherein each processor core can be a CPUor a GPU. The memory 104 can be located on the same die as the processor102, or can be located separately from the processor 102. The memory 104can include a volatile or non-volatile memory, for example, randomaccess memory (RAM), dynamic RAM, or a cache.

The storage 106 can include a fixed or removable storage, for example, ahard disk drive, a solid state drive, an optical disk, or a flash drive.The input devices 108 can include a keyboard, a keypad, a touch screen,a touch pad, a detector, a microphone, an accelerometer, a gyroscope, abiometric scanner, or a network connection (e.g., a wireless local areanetwork card for transmission and/or reception of wireless IEEE 802signals). The output devices 110 can include a display, a speaker, aprinter, a haptic feedback device, one or more lights, an antenna, or anetwork connection (e.g., a wireless local area network card fortransmission and/or reception of wireless IEEE 802 signals).

The input driver 112 communicates with the processor 102 and the inputdevices 108, and permits the processor 102 to receive input from theinput devices 108. The output driver 114 communicates with the processor102 and the output devices 110, and permits the processor 102 to sendoutput to the output devices 110. It is noted that the input driver 112and the output driver 114 are optional components, and that the device100 will operate in the same manner if the input driver 112 and theoutput driver 114 are not present.

An integration of a control system and architecture is proposed for acomplex networked system of microfluidic channels that crisscross a 3DIC in the x, y, and z dimensions of the IC to deliver fluid to interiorregions of the IC as a means to dissipate heat. As used herein, the term“fluid” refers to any type of matter or substance that continuallydeforms (flows) under an applied shear stress, including liquids, gases,plasmas and the like. The control system (e.g., a controller) utilizesmodeled and measured temperatures of both the fluid and the IC (e.g.,components, parts and/or areas of the IC) to determine how todynamically route the fluid through the IC via the microfluidic channelsgiven the constraints of the “ideal” and “tolerable” operatingconditions for sub-circuits within the IC. The controller is provided onthe same IC it is monitoring or on a different IC.

Temperature, pressure, activity and/or power sensors are provided at oneor more components of the IC and/or at different internal or externalregions of the IC such that temperatures can be monitored and detectedby the control system. Temperatures are either explicitly measured orestimated via one or more temperature, pressure, activity and/or powersensors. A sensor is configured to sense, measure and/or detect one ormore states of the IC at one or more locations, and report theinformation to a controller. A state of the IC can be representative ofa temperature of the IC, a component of the IC, or region of the IC, andcan be associated with a specific location within the IC.

For example, a temperature sensor measures in real-time the temperaturein the proximity of the sensor, and provides a temperature measurementto the controller. The temperature sensors provide temperatureinformation in the form of temperature feedback information (e.g.,measurement signals) to the control system such that the control systemcan determine how to dynamically route the fluid through the IC via themicrofluidic channels given the constraints of the “ideal” and“tolerable” operating conditions for sub-circuits within the IC.

A pressure sensor measures in real time a pressure of a fluid flowingthrough a channel. A pressure sensor is used independently or in tandemwith a temperature sensor and/or other sensors and models to ensure thatthe IC is within the target operating regime. In one aspect, a pressuresensor is used to measure the rate of flow of fluid through the IC aswell to detect a malfunction in other components and to compensateaccordingly. For instance, if one of the other sensors or components ismalfunctioning or “noisy”, and the pressure sensors can be used tocorrect for this irregularity or dial down (i.e., reduce) theaggressiveness of the power management regime. Thus, inconsistencies inmeasurements the different sensors are measuring or in values the modelsproject can be reduced.

A power sensor measures or detects in real-time the power consumption ofa component within the IC, which can also be correlated to a temperaturevalue. The measured or detected power consumption is used by the sensoror the controller to calculate, for example, a temperature of thecomponent such that the control system determines how to dynamicallyroute the fluid through the IC via the microfluidic channels given theconstraints of the “ideal” and “tolerable” operating conditions forsub-circuits within the IC.

In some aspects, one or more sensors (e.g., temperature or pressuresensors) are provided within or adjacent to one or more channels tomeasure a characteristic (e.g., temperature or pressure) of the fluidtherein.

Microelectromechanical System (MEMS)-based switches are provided withinthe microfluidic channel network (e.g., within a channel, betweenchannels, at a channel intersection, or collectively at a channeljunction) and are configured to open and close to permit or prevent fullor partial flow of the fluid through a channel, an intersection, or anarea of the IC based on control commands received from the controlsystem. Thus, the flow/flows of one or more fluids are regulated by oneor more MEMS-based switches based on control signals received from thecontrol system. Furthermore, a fluid flowing through the MEMS-basedswitch is routed or rerouted from one channel to a same or differentchannel within the microfluidic channel network by the MEMS-basedswitch. By routing and rerouting fluid within the microfluidic channelnetwork, different parts of the IC can be targeted for cooling.

In one aspect, the flow/flows of one or more fluids are increased in oneor more channels via control of one or more MEMS-based switches when acondition is satisfied (e.g., when temperature state, a power state, oran operational state satisfies a first condition). In addition oralternately, flow/flows of one or more fluids are maintained in a basestate, decreased or stopped in one or more channels via control of oneor more MEMS-based switches when the first condition is not satisfied orwhen a second condition is satisfied.

For example, the first condition is whether an upper threshold,corresponding to a temperature state, a power state, or an operationalstate (e.g., high temperature state, high power state, or highoperational state), is met or exceeded (i.e., above the upperthreshold), and the second condition is whether a lower threshold,corresponding to a temperature state, a power state, or an operationalstate (e.g., low temperature state, low power state, or low operationalstate), is met or exceeded (i.e., below the lower threshold).

It will be understood that one or more conditions, thresholds and/ortargets have equal, lesser or higher priority that should, could or needto be met and many different operating regimes that are used to controlone or more MEMS-based switch throughout the system for controlling theflow of fluid. For example, a component of higher priority receivespriority in cooling via the regulation of fluid in a nearby channel overa component of lesser priority. In addition or in the alternative, afirst component of equal priority receives priority in cooling via theregulation of fluid in a nearby channel over a second component of equalpriority based on a critical target (e.g., temperature or powerthreshold) being met or exceeded by the first component.

As used herein, a “priority in cooling” refers to a routing of fluid orof more fluid to a channel in proximity to an area of the IC whencompared to an amount of fluid routed to a channel in proximity toanother area of the IC. Thus, in one or more aspects, the IC is dividedinto different areas that do or do not overlap. An “area of the IC” is aregion, area, part and/or component of the IC and each region, area,part and/or component of the IC are assigned a priority level which arethe same or different than other priority levels for managing theregulation of fluid passing through different areas of the IC via thechannel network. Furthermore, one or more regions, areas, parts and/orcomponents are measured by a sensor, and, thus, one or more sensorscould also be assigned a priority level that is correlated to the areaof the IC the sensor is measuring.

It will be understood that the terms gate, switch, valve, MEMS switch,MEMS-based switch, MEMS gate and MEMS-based gate are usedinterchangeably, unless specifically noted otherwise, and that one termcan replace or be combined with another term in one or more aspects.These terms can generally be referred to as MEMS, MEMS-based devices,aperture regulating mechanisms, port regulating mechanisms, openingregulating mechanisms, ingress control mechanisms, egress controlmechanisms, fluid flow control mechanisms and the like, or can includeone or more aperture regulating mechanisms, port regulating mechanisms,port opening/closing mechanisms, ingress control mechanisms, egresscontrol mechanisms, fluid flow control mechanisms and the like.

In one or more aspects, one or more types of fluid are used and/or mixedto control and optimize heat dissipation. The different fluids each havedifferent thermal absorption properties and/or different levels ofcompressibility. For example, a first fluid is used in a channel orthroughout the channel network under normal temperature conditions, anda second fluid with a higher thermal absorption or compressibility isinjected or volume increased upon detection by the control system of atemperature of a components, parts and/or area of the IC that exceeds athreshold. In one aspect, the first fluid is replaced by the secondfluid by the control of valves, gates, and/or MEMS-based switches. Inanother aspect the first fluid is supplemented (i.e., mixed) with thesecond fluid by the control of valves, gates, and/or MEMS-basedswitches. A concentration of the mixture can also be monitored by asensor and/or the controller and controlled based on the control of thevalves, gates, and switches.

The control system provides dynamic control of the MEMS-based switchesby actively and continuously monitoring and modifying the state (e.g.,opened state, closed state, and any degree therebetween) of MEMS-basedswitches to control the rate of ingress and egress of fluid between theinput and output channels of the IC, as well as the degree of mixing offluid of distinct temperatures from points of ingress to points ofegress. This technique allows for sub-circuits, such as ALUs, to operateat peak performance for longer periods without having to be asaggressively throttled using dynamic voltage and frequency scaling(DVFS). Accordingly, the dynamic control of the fluid throughout themicrofluidic channel network provides pinpoint accuracy of thedispersion of heat throughout the IC based on a current environment orcondition, and addresses the dispersion of heat at a component levelwithin the IC.

In one or more aspects, internal and/or external pumps are furtherprovided for circulating the fluid through the IC. For example, one ormore external pumps are provided to inject fluid into one or morechannels or withdraw fluid from one or more channels. In addition or inthe alternative, one or more internal pumps are provided within themicrofluidic channel network to do the same. In one or more aspects, oneor more MEMS-based switches include a pump. The pumps further help tocontrol the rate of ingress and egress of fluid between the input andoutput channels of the IC, as well as the degree of mixing of fluid ofdistinct temperatures from points of ingress to points of egress.

It will be appreciated that the integrated control system architectureis applicable to microfluidic cooling either in conjunction with fullimmersion system or as a standalone cooling solutions. A standalonecooling solution includes a separate cooling method for the full system.For example, some standalone techniques include regular air-cooling orliquid cooling in which the cooling liquid is stored in a reservoir ortank and provided to the channels by injection or pumping. The liquid(or other fluid) is further cooled after passing through the IC andrecycled in a closed system.

Dynamic control of the fluid throughout the microfluidic channel networkreduces the heat transfer problem created by 3D stacking by allowingfluid to be directly routed to the parts of the IC that are in most needof it, when they need it. For example, this technology when utilizedwith full server immersion system or a separate, standalone microfluidicheat dissipation system more effectively dissipates heat from thehottest components, which can be used to create commerciallydifferentiated processors with more aggressive designs (e.g., feasiblystacking last level cache (LLC) on top of the processor) and operatingpoints.

More effective use of microfluidic cooling is achieved through activecontrol of fluid flow based on dynamically determined requirements.Therefore, higher energy density can be tolerated, allowing variouscircuits to be located more densely. By bringing communicatingcomponents closer together, wire length, and hence resistance, isdecreased, which saves energy. In addition, higher bandwidth betweencomponents can be achieved at reduced energy cost, which could beessential for a number of important data center workloads that do notcache well.

Allowing for pinpoint control of heat dissipation grants the powermanagement subsystem a further degree of freedom in the form of fluidrouting over the traditional techniques of DVFS and power gating. Suchcontrol enables more aggressive chip designs in the data center space,with higher performance per watt.

FIG. 2 illustrates an example MEMS-based switch 20 according to one ormore embodiments. The switch 20 includes multiple input ports 22 a, 22 band 22 c, multiple output ports 24 a, 24 b, 24 c and 24 d, and one ormore internal pathways or channels (not shown) therebetween. One or morefluids A, B and C flow into the switch 20 through the input ports 22 a,22 b and 22 c and flow out of the switch 20 through the output ports 24a, 24 b, 24 c and 24 d. Fluids A, B and C of potentially differentpressures and temperatures are mixed in differing quantities or volumeswhen routed through the switch 20 to the output ports 24 a, 24 b, 24 cand 24 d. Thus, the switch 20 is configured with multiple internalintersecting channels and gates for mixing one or more fluids A, B andC. For example, the output flow for output port 24 a is closed such thatno fluid flows out of output port 24 a. The fluid in output flow foroutput port 24 b is a combination of 0.25A, 0.50B and 0.25C, the fluidin output flow for output port 24 c is a combination of 0.50A and 0.50B,and the fluid in output flow for output port 24 d is a combination of0.25A and 0.75C.

FIG. 3 illustrates an example 3D IC 30 with a microfluidic channelnetwork according to one or more disclosed embodiments. It will beunderstood that the terms IC and chip are used interchangeablythroughout. The IC 30 is immersed in fluid 31 (i.e., immersive fluid)such that the fluid 31 flows from one or more input ports 32 a, 32 b, 32c and 32 d of the IC 30 to the one or more output ports 34 a, 34 b, 34 cand 34 d of the IC 30 through one or more channels of a microfluidicchannel network 36 of the IC 30. Each input port 32 a, 32 b, 32 c and 32d and output port 34 a, 34 b, 34 c and 34 d is provided with aMEMS-based switch or gate controlled by the control system forcontrolling the ingress and egress of the fluid 31 into and from the IC30. For example, MEMS-based switches or gates provided at input port 32c and output ports 34 a and 34 c are closed, while MEMS-based switchesor gates provided at input ports 32 a, 32 b and 32 d and output ports 34b and 34 d are open or at least partially open.

External pumps (not shown) can also be provided to inject the fluid 31into the IC 30 or withdraw the fluid 31 from the IC. It will beappreciated that the IC 30 can also be implemented with a standalonecooling solution (e.g., a separate microfluidic heat dissipationsystem). In such a system, the IC 30 is not be immersed in the fluid 31and external pumps (not shown) are provided to inject the one or morefluids (e.g., fluids A, B and C) into the IC 30 or withdraw the fluid 31from the IC.

The channel network 36 traverses one or more layers of the IC 30 andincludes multiple channel intersections 38 (e.g., intersection 38 a andintersection 38 b) where a MEMS-based switch (e.g., switch 20 describedin FIG. 2) is provided. It will be appreciated that a MEMS-based switchis provided at some, none or all channel intersections 38, and/or thatone or more MEMS-based switches is provided in one or more channels ofthe channel network 36.

As shown in FIG. 3, the state of each of the MEMS-based switches isdynamically controlled by a control system (e.g., a controller) based onsensed temperature conditions within the IC 30. The states of theMEMS-based switches and their respective input/output ports areconfigured by the controller on a real-time basis to be in an openstate, closed state or a partially closed/open state based on thecontrol of the controller. For example, the MEMS-based switch at channelintersection 38 a has each of its input/output ports at least partiallyopen such that fluid enters and exits each channel connected thereto. Onthe other hand, the MEMS-based switch at channel intersection 38 b hastwo of its input/output ports closed such that fluid does not flowwithin two of the channels connected thereto. The MEMS-based switchescan be controlled independently or in cooperation with each other basedon the determined flow of the fluid that the controller implements.

In one or more aspects, in addition to or in alternative to reactivebased cooling, the control system for the MEMS switches described aboveco-operates with power distribution control of the chip such that thenecessary cooling is proactively provisioned based on measurements andmodels. For example, when a processor core enters a “boosted” or “turbo”state, cooling near that core is increased proactively using the MEMSswitch infrastructure. Thus, the state of one or more MEMS-based switchis controlled based on an operational state of a component within the IC30 such that fluid flowing near the component is controlled toeffectively dissipate heat generated by the component in a proactivemanner.

FIG. 4 illustrates another example 3D IC 40 with a microfluidic channelnetwork according to one or more disclosed embodiments. The IC 40 is oris not be immersed in a fluid. The 3D IC 40 includes input ports 41 aand 41 b (i.e., ingress ports) and output ports 41 c and 41 d (i.e.,egress ports) and microfluidic channels 43 a, 43 b, 43 c and 43 dtherebetween for carrying one or more fluids (e.g., fluid A and fluid B)therein. The channels 43 a, 43 b, 43 c and 43 d are of the same or ofdiffering widths.

The 3D IC 40 further includes IC components 44 a and 44 b that arelocated adjacent to channels 43 a and 43 c, respectively. However, itwill be appreciated that the location of IC components and channels arenot limited thereto. For example, each or fewer channels have an ICcomponent adjacent thereto or in proximity therewith. A channel can beadjacent to or in proximity to more than one IC component, which can belocated on same or opposing sides of the channel. An IC component canalso have more than one channel located adjacent thereto or in proximitytherewith. Furthermore, while FIG. 4 illustrates channels in the x-yplane, channels can also extend in the z-plane. Thus, a channel adjacentor in proximity to a component can be a channel that extends in thex-direction, the y-direction, the z-direction or a combination thereof.

An IC component is any component within or on a surface of the IC 40that generates heat due to being in an operational state. The 3D IC 40further includes a controller 45 electrically coupled to (i.e., inelectrical communication with) gates 46 a, 46 b, 46 c and 46 d, sensors47 a, 47 b, 47 c and 47 d, and a switch 48 that includes input ports 48a and 48 b (i.e., ingress ports) and output ports 48 c and 48 d (i.e.,egress ports) with additional gates 49 a, 49 b, 49 c and 49 d coupledthereto or integrated therein. Furthermore, gates 46 a, 46 b, 46 c and46 d can each be part of a MEMS gate or switch.

The microfluidic channels 43 a, 43 b, 43 c and 43 d carry one or morefluids therein (e.g., fluid A and fluid B). For example, fluids A and Bare the same type of fluid having a same temperature or having differingtemperatures. For example, the fluid A in channel 43 a, which runs alongor traverses various sensors and IC components, is typically warmer thanthe fluid B in channel 43 b, which runs along none or fewer IC sensorsand IC components. Thus, fluid A, when mixed with fluid B within theswitch 48, is used to cool down fluid B. Alternatively, fluids A and Bare different such that channel 43 a carries a first type of fluid A andchannel 43 b carries a second type of fluid B different than the firsttype. Thus, the fluids A and B can be mixed by the switch 48 to regulatethe properties of the mixed fluid exiting the switch 48 into channels 43c and/or 43 d. For instance, the switch 48 in FIG. 4 routes adisproportionate amount of a cool liquid (e.g., fluid B) from the lowerchannel 43 b to the upper egress port 41 c via upper channel 43 c inorder to be able to better cool the second component 44 b. This isachieved, for example, by narrowing the apertures of gates 49 a and 49 dand widening the apertures of gates 49 b and 49 c such that the fluidpressure forces a disproportionate amount of a cool liquid (e.g., fluidB) from the lower channel 43 b to the upper egress port 41 c via upperchannel 43 c.

The switch 48 is a multichannel MEMS-based switch and includes one ormore internal channels, one or more internal gates and one or more pumpswhich are configured to regulate the flow and the route of fluids A andB and, furthermore, enable the mixing of fluids A and B. The internalchannels can intersect with one another. The opened, partially opened orclosed state (i.e., the opening width) of the gates 49 a, 49 b, 49 c and49 d and internal gates (not shown) are controlled by the controller 45to regulate the temperature of the components 44 a and 44 b.

For example, all or part of fluid A from channel 43 a and none of fluidB from channel 43 b is directed by switch 48 to channel 43 c, and all orpart of fluid B from channel 43 b and none of fluid A from channel 43 ais directed by switch 48 to channel 43 d. Alternatively, all or part offluid A from channel 43 a and none of fluid B from channel 43 b aredirected by switch 48 to channel 43 d, and all or part of fluid B fromchannel 43 b and none of fluid A from channel 43 a are directed byswitch 48 to channel 43 c. Additionally or alternatively, fluids A and Bare at least partially mixed within the switch 48 such that a mixture offluids A and B is directed to channel 43 c and/or channel 43 d. It willbe appreciated that any mixture or non-mixture of fluids A and B isprovided by the switch 48 to channels 43 c and 43 d based on the controlsignals provided by the controller 45 to the switch 48. The controlsignals are generated by the controller 45 based on a temperature,explicit or implicit, of the corresponding fluid, area, IC component,region, or other monitored part of the IC 40 such that a temperature ofthe IC 40 is regulated, and, more particularly, such that an internaltemperature of the IC 40 is regulated.

Sensors 47 a, 47 b, 47 c and 47 d are one of temperature, pressure,activity or power sensors, as similarly described above, and providemeasurement feedback information (i.e., measurement data) to thecontroller 45. The sensors 47 a, 47 b, 47 c and 47 d output rawmeasurement data (i.e., sensed data) or processed measurement data. Forexample, for outputting processed measurement data, a sensor includesone or more processors for processing the raw measurement data andoutputting processed measurement data. Thus, the sensors 47 a, 47 b, 47c and 47 d are configured to sense, detect and/or measure a state of theIC 40 such that the state of the IC 40 is representative of atemperature of the IC 40, a component of the IC 40 or region of the IC40.

The controller 45 is configured to collect and process the receivedmeasurement feedback information (raw or processed) to instruct, viacontrol signals, any of gates 46 a, 46 b, 46 c, 46 d, 49 a, 49 b, 49 cand 49 d, and internal gates (not shown) of switch 48 for regulating theflow of fluids A and B within the channels for regulating a temperatureof the IC 40. For example, the controller 45, while monitoring one ormore components, sensors, areas, etc. of the IC 40, detects ordetermines that a temperature in the IC 40 has exceeded or is likely toexceed a threshold, and the controller 45 configures one or moreMEMS-based devices via control signals such that fluid, additional fluidand/or cool fluid is routed to at least one channel located at theregion of the IC 40 that corresponds to the temperature increase.

The controller 45 includes one or more processors for receivingmeasurement feedback information, processing and/or analyzing themeasurement feedback information, and providing control signals to oneor more elements described herein. While the controller 45 is depictedas part the IC 40 in FIG. 4, the location of the controller 45 is notlimited thereto and can be provided elsewhere, even on another IC.

Gates 46 a, 46 b, 46 c and 46 d are referred to as external gates orswitches and gates 49 a, 49 b, 49 c and 49 d are referred to as internalgates or switches. Furthermore, it will be understood that each gate 46a, 46 b, 46 c, 46 d, 49 a, 49 b, 49 c and 49 d, and internal gate (notshown) provided within the switch 48 can be any type of gate, valve,switch or the like (e.g., a MEMS gate, valve or switch) that can becontrolled between fully open and fully closed states, and/or any degreetherebetween for regulating the flow of a fluid therethrough (e.g.,through a corresponding port, aperture or opening). Thus, each gate isconfigured with gate functionality and/or switch functionality.

For example, one or more MEMS-based devices can be or can include a MEMSgate, and provides gate functionality such that the MEMS-based devicesact as gates where fluid is prevented from exiting or entering a certainpart of the IC via the walling off of channels. That is the MEMS gate iseither fully open or fully closed.

In addition, one or more MEMS-based devices can be or can include a MEMSswitch, and provides switch functionality such that the MEMS-baseddevice acts as switch for a single channel or a multichannel junction(i.e., single channel switch and multichannel switch). A single channelswitch controls the rate of flow of fluid through a single channel bymodulating the minimum width of the channel opening or aperture. Amultichannel switch modulates the minimum width of one or more channelopenings or apertures, and can also control the mixing of fluids ofdifferent temperatures and/or types as well as selecting, which portsthe fluid/fluids enter and exit out of.

FIG. 5 illustrates a block diagram of an example control system 50implemented by one or more disclosed embodiments. The control system 50includes a controller 52 that sends updates in the form of controlsignals to MEMS gates and switches 54 based on data collected from oneor more sensors and/or one or more models, referred to as units 56 a, 56b and 56 c, and based on analyzing the switch states (e.g., open, closedor partially open) of the MEMS gates and switches 58.

Unit 56 a is one or more sensors and/or one or more memory devices, andprovides IC subcomponent metadata for an IC component. The ICsubcomponent metadata includes at least one of location, temperature,operating state and additional statistics with respect to a sensorand/or an IC component in proximity to the sensor.

Unit 56 b is one or more sensors and/or one or more memory devices, andprovides fluid metadata of a fluid in proximity to a sensor. The fluidmetadata includes at least one of location, temperature, pressure andadditional statistics with respect to a fluid and/or an IC component inproximity to the sensor.

Unit 56 c is one or more memory devices storing one or more models andother data, and provides local and global constraints stored thereinwith respect to a particular IC component and/or the IC itself. Thelocal and global constraints are provided and/or stored by a user (e.g.,a programmer) and adapted, modified and/or updated based on the designof the IC and/or for a particular IC component. The local and globalconstraints can include power constraints that correspond to a maximumtemperature an IC and/or an IC component is designed to withstand, andthe control of fluid (e.g., timing, rate of flow, temperature, pressure,route, direction, mixing, etc.) is adapted based on such powerconstraints. The local and global constraints can additionally includemaximum temperatures tolerable by an IC and/or an IC component based onthe thermal sensitivity of the IC and/or the component. The local andglobal constraints can be further provided for forced power states andoperating modes of the IC and/or an IC component, and the control offluid is adapted thereto. Thus, the controller 52 is configured tocontrol one or more fluids according to the local and global constraintsof a specific IC, IC component and/or the design or implementationthereof.

The controller 52 further analyzes (e.g., receive, monitor and/or track)state information 58 of a MEMS gate or switch such that the state of theMEMS gate or switch can be controlled and configured on a real timebasis according to other information collected by the controller 52.

FIG. 6 is a flow diagram of a cooling method 600 implemented by one ormore disclosed embodiments. As described above, the IC includes anetwork of microfluidic network of channels, at least one sensor and atleast one MEMS-based device disposed within the microfluidic network ofchannels and configured to regulate a flow of fluid within themicrofluidic network of channels. Accordingly, the method 600 includesmonitoring and detecting, by the at least one sensor, a state of the IC(operation 62). A controller determines whether a flow of fluid in themicrofluidic network of channels should be changed based on a currentstate of the IC (operation 64), and returns to operation 62 if the flowof flow of fluid in the microfluidic network of channels should not bechanged. If the flow of fluid in the microfluidic network of channelsshould be changed, the controller sends controls signals based on thestate of the IC, which are received by the at least one MEMS-baseddevice (operation 66). The at least one MEMS-based device regulates theflow of fluid within the microfluidic network of channels based on thecontrol signals received by the at least one MEMS-based device on areal-time basis based on changes detected in the state of the IC(operation 68).

FIG. 7 illustrates another example 3D IC 70 with a microfluidic channelnetwork. The IC 70 includes an input port 71 and an output port 72 forallowing fluid to flow into and out of the IC 70. The IC 70 includes afirst channel 73 a and a second channel 73 b for carrying the fluidtherein. The first channel 73 a and the second channel 73 b areconnected by a single channel MEMS-based device 74, which is implementedas either a gate or a switch for regulating the flow of fluid to thesecond channel 73 b. The IC 70 further includes a sensor 75 whichmeasures a state of the IC 70, including a state of component 76 that isadjacent to the second channel 73 b. The sensor 75 transmits measurementsignals to the controller 77, which controls the state of the MEMS-baseddevice 74 to regulate the flow of fluid to the second channel 73 b. Inparticular, the controller 77 transmits control signals to theMEMS-based device 74 to regulate the flow of fluid to the second channel73 b and to regulate the temperature in the area of the IC 70 proximateto the second channel 73 b. While the controller 77 is illustrated aspart of the IC 70, it will be appreciated that the controller 77 can belocated on a device external to the IC 70.

In view of the above, a MEMS-based network of active switches isincorporated into a 3D IC that can dynamically modulate the flow androuting of fluid within the microfluidic channels within the 3D IC. Thenetwork of switches are controlled using active measurements provided bysensors and/or modeling of heat dissipation in various parts of the 3DIC during operation. Thus, the control system and architecture allowsfor dynamic microfluidic cooling of a 3D IC with pin point accuracy.Specific areas within the 3D IC are cooled on “as needed” basis with ahigher degree of urgency than other areas of the 3D IC.

One or more control systems, including a controller, disclosed herein isconfigured to utilize any combination of data sources, includinglocalized power and temperature statistics, activity measurements,machine specifications, and models composed thereof and/or emulatingthem to control the states of the individual MEMS-based switchesthroughout the IC. The control system can interface with the chip'sother power and temperature management systems. The control system iseither centralized or decentralized.

The control system, via coordinating the MEMS-based switches, controlsthe ingress and egress of fluid from the IC. For example, the controlsystem controls which external MEMS-based switches (e.g., gates 46 a, 46b, 46 c, 46 d) are open or closed, and controls the width of theaperture or port, etc., of the MEMS-based switches to control the volumeof fluid flowing through the aperture or port.

The control system, via coordinating the MEMS-based switches, controlsmixing of fluid of different temperatures based on the aforementioneddata sources, for example, power, temperature, etc., at various pointsof the IC as well as the temperature of the discrete channels of fluidthat mix at channel junctions governed by the switches.

The control system, via coordinating the MEMS-based switches, controlsgating off parts of the IC by closing MEMS-based switches such that thefluid does not flow there (i.e., does not flow in a specific channel).

A network of MEMS-based switches throughout the IC both within theinterior and at the exterior provide gate and/or switch functionalities.For example, one or more MEMS-based switches provide gate functionalitysuch that the MEMS act as gates where fluid is prevented from exiting orentering a certain part of the IC via the walling off of channels. Thatis, the gate is either fully open or fully closed. As another example,one or more MEMS-based switches provide switch functionality such thatthe MEMS act as switches for single channels and multichannel junctions(i.e., single channel switches and multichannel switches). A singlechannel switch controls a rate of flow of fluid through a single channelby modulating the minimum width of the channel opening or aperture. Amultichannel switch controls a rate of flow of fluid and/or the mixingof fluids of different temperatures and/or types as well as selecting,which ports the different fluids exit out of.

One or more control systems disclosed herein includes internal controland monitoring network(s) for propagating and updating switch and gatestates, monitoring fluid thermals, pressures and velocity, and forinterfacing with IC components/subcomponents that can direct high levelpolicies.

Instruction set architecture extensions can be provided for queryingstate and expressing policies to the control system. For example, thecontrol system is configured to query the state of each gate and switch,and transmit updates (e.g., control signals) to each gate and switch toupdate their state. Instruction set architecture extensions include theaddition of model specific registers for controlling MEMS switch andgate states, model specific registers for controlling high-level coolingpolicies on-chip, and model specific registers that can be queried andset to report the state of the switches/gates and fluid at differentlocations. The state of the switches and gates include informationcorresponding to one or more of the mixing ratios at switches, degreegates are open/closed, location, etc. The state of the fluids caninclude information corresponding to fluid pressures and temperatures indifferent channels, and heat differentials over time, location, etc.

The instruction set architecture extensions provide instructions thatmanipulate cooling policies, instructions to manipulate the state ofMEMS switch and gate states, instructions to query MEMS switch and gatestates, and instructions to query fluid temperatures, pressures,velocities throughout the IC.

It will be appreciated that decision making for controlling the state ofthe gates and switches by the control system can be made by software,hardware, firmware or a combination thereof.

The use of the aforementioned MEMS concepts can be further applied to anexternal switching system. For example, a control system (e.g., acontroller) can monitor, control or receive information corresponding toseparate external channels that are external to the IC that supply thefluid to the internal channels in the IC that are switched using MEMSgates and switches (e.g., for non-immersive systems or for immersivesystems coupled with separate external channels). The switching and/orgating of external channels is based on at least one of internal fluidsensor data, eternal fluid sensor data, internal gate and switch states,and external gate and switch states.

The control system of the IC is external to the IC, internal to the IC,or internal to the IC and integrated with an external control system.Thus, an external or coupled internal-external control system can beprovided for switching the fluid fed to the IC.

Furthermore, an IC can be part of a network of ICs that exchangeinformation with each other and/or share fluid. For example, a chain ofICs includes at least one upstream IC and at least one downstream ICthat share information such that a controller of each IC or a globalcontroller of the network of IC can make global decisions that impactother ICs in the network. For example, a temperature state of one IC inthe network of ICs can affect (or can be anticipated to affect) atemperature state of one or more other ICs in the network, and/or thetemperature of the fluid delivered to a downstream IC. Thus, globaldecisions can be made by the control system for the network of ICs suchthat internal switches and gates of individual ICs are controlled suchthat heat is dissipated effectively on an individual and/or globalscale. Accordingly, one or more ICs in the network of ICs can beconfigured to transmit any of the internal or external switch, gate, orcontroller states in digital form to another IC over any medium. Inaddition, interfaces can be provided between internal to externalcontrol and monitoring networks for controlling and/or coordinatingswitch and gate states and for integrating and/or coordinatingtemperature and pressure sensors.

It should be understood that many variations are possible based on thedisclosure herein. Although features and elements are described above inparticular combinations, each feature or element can be used alonewithout the other features and elements or in various combinations withor without other features and elements.

The methods provided can be implemented in a general purpose computer, aprocessor, or a processor core. Suitable processors include, by way ofexample, a general purpose processor, a special purpose processor, aconventional processor, a digital signal processor (DSP), a plurality ofmicroprocessors, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, Application Specific IntegratedCircuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, anyother type of integrated circuit (IC), and/or a state machine. Suchprocessors can be manufactured by configuring a manufacturing processusing the results of processed hardware description language (HDL)instructions and other intermediary data including netlists (suchinstructions capable of being stored on a computer readable media). Theresults of such processing can be maskworks that are then used in asemiconductor manufacturing process to manufacture a processor whichimplements aspects of the embodiments.

The methods or flow charts provided herein can be implemented in acomputer program, software, or firmware incorporated in a non-transitorycomputer-readable storage medium for execution by a general purposecomputer or a processor. Examples of non-transitory computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

What is claimed is:
 1. An integrated circuit (IC) comprising: aplurality of channels configured to carry a fluid therein throughinternal portions of the IC, wherein the plurality of channels include afirst channel and a second channel; at least one sensor configured tosense at least one state of the IC; and a microelectromechanical system(MEMS)-based device disposed at a junction connecting at least the firstchannel and the second channel of the plurality of channels, wherein theMEMS-based device is configured to: receive control signals from acontroller based on the at least one state of the IC; and regulate aflow of the fluid from the first channel to the second channel based onthe control signals.
 2. The IC of claim 1, wherein the plurality ofchannels include a third channel connected to the MEMS-based device atthe junction, and the MEMS-based device is configured to regulate a flowof the fluid from the third channel to the second channel based on thecontrol signals.
 3. The IC of claim 1, wherein the plurality of channelsinclude a third channel connected to the MEMS-based device at thejunction, and the MEMS-based device is configured to regulate a flow ofthe fluid from the first channel to the third channel based on thecontrol signals.
 4. The IC of claim 1, wherein the MEMS-based deviceincludes a plurality of ingress ports and at least one egress port, eachport of the plurality of ingress ports and the at least one egress portis connected to one of the plurality of channels, and the MEMS-baseddevice is configured to regulate a flow of the fluid from the pluralityof ingress ports to the at least one egress port based on the controlsignals.
 5. The IC of claim 1, wherein the MEMS-based device includes atleast one ingress port and a plurality of egress ports, each port of theat least one ingress port and the plurality of egress ports is connectedto one of the plurality of channels, and the MEMS-based device isconfigured to regulate a flow of the fluid from the at least one ingressport to the plurality of egress ports based on the control signals. 6.The IC of claim 1, further comprising: an ingress IC port configured toallow the fluid to flow into the IC; an egress IC port configured toallow the fluid to flow out of the IC; an ingress MEMS-based devicedisposed at the ingress IC port and configured to regulate a flow of thefluid into the IC based on the at least one state of the IC; and anegress MEMS-based device disposed at the egress IC port and configuredto regulate a flow of the fluid out of the IC based on the at least onestate of the IC.
 7. The IC of claim 1, wherein the at least one state ofthe IC is associated with a temperature at a location within the IC, andthe MEMS-based device is configured to regulate the flow of the fluidsuch that the temperature is regulated on a real-time basis.
 8. The ICof claim 1, further comprising: the controller configured to receivemeasurement information from the at least one sensor that corresponds tothe at least one state of the IC, and generate the control signals basedon the measurement information.
 9. The IC of claim 1, wherein theMEMS-based device is configured to be switched between a closed stateand an open state based on the control signals for regulating the flowof the fluid.
 10. The IC of claim 1, wherein the MEMS-based deviceincludes at least one pump that regulates the flow of the fluid based onthe control signals.
 11. An integrated circuit (IC) comprising: a firstsensor configured to measure a state of the IC at a first location ofthe IC; a microfluidic network of channels configured to carry a fluidtherein through internal portions of the IC, wherein the microfluidicnetwork of channels include a first channel that is disposed inproximity to the first location such that a temperature at the firstlocation is regulated by a flow of the fluid in the first channel; and afirst microelectromechanical system (MEMS)-based device disposed withinthe microfluidic network of channels, wherein the first MEMS-baseddevice is configured to: receive control signals from a controller basedon the state of the IC at the first location; and regulate the flow ofthe fluid in the first channel based on the control signals.
 12. The ICof claim 11, further comprising: a second sensor configured to measure astate of the IC at a second location of the IC; a second channelincluded in the microfluidic network of channels and disposed inproximity to the second location such that a temperature at the secondlocation is regulated by a flow of the fluid in the second channel; anda second MEMS-based device is configured to receive control signalsbased on the state of the IC at the second location and configured toregulate the flow of the fluid in the second channel based on thecontrol signals.
 13. The IC of claim 11, wherein the first location isat an internal location of the IC, the state of the IC at the firstlocation corresponds to a state of a component of the IC disposed at thefirst location of the IC, and the state of the component is at least oneof a temperature state of the component, a power state of the componentor an operational state of the component.
 14. The IC of claim 11,wherein the first sensor is configured to measure the state of the IC atthe first location on a real-time basis, and the first MEMS-based devicereceives the control signals based on changes in the state of the IC atthe first location such that the flow of the fluid in the first channelis regulated on a real-time basis based on the changes in the state ofthe IC at the first location.
 15. The IC of claim 11, wherein the firstMEMS-based device is configured by the control signals to change theflow of the fluid in the first channel when the state of the IC at thefirst location satisfies a temperature regulating condition.
 16. The ICof claim 11, further comprising: the controller configured to receivemeasurement information from the first sensor that corresponds to thestate of the IC at the first location, and generate the control signalsbased on the measurement information.
 17. The IC of claim 11, whereinthe IC is part of a network of ICs, and the first MEMS-based device isconfigured to receive network control signals based on a state ofanother IC in the network of ICs and configured to regulate a flow ofthe fluid in the microfluidic network of channels based on the networkcontrol signals.
 18. A method of cooling an integrated circuit (IC)including a microfluidic network of channels, at least one sensor and atleast one microelectromechanical system (MEMS)-based device disposedwithin the microfluidic network of channels and configured to regulate aflow of fluid within the microfluidic network of channels, the methodcomprising: monitoring, by the at least one sensor, a state of the IC;receiving, by the at least one MEMS-based device, control signals from acontroller based on the state of the IC; and regulating, by the at leastone MEMS-based device, the flow of fluid within the microfluidic networkof channels based on the control signals received by the at least oneMEMS-based device on a real-time basis based on changes detected in thestate of the IC.
 19. The method of claim 18, wherein the state of the ICis associated with a temperature at a location within the IC, and the atleast one MEMS-based device is configured to regulate the flow of thefluid such that the temperature is regulated on a real-time basis. 20.The method of claim 19, wherein the state of the IC is a state of acomponent disposed within the IC, and the state of the component is atleast one of a temperature state of the component, a power state of thecomponent or an operational state of the component.